Methods: Lava™ (3M/ESPE) was used as Y-TZP material. VITA VM®9 (Vita-Zahnfabrik) was used as the veneering porcelains. Lava™ were sectioned into 30 discs with thicknesses of: 1 mm, 2 mm, and 5 mm respectively. The powder water slurry mix was condensed into a mold to form a button with a diameter of 4 mm and height of 3 mm. Specimens were subjected to a shear bond test using a 4 mm notched blade on universal testing machine (Instron) with a crosshead speed of 0.5 mm/min.
Statistical analysis was done using ANOVA and Tukey post hoc test at p= 0.05.
Results: Shear bond strength of VITA VM®9 to Lava™ with a thickness of 1 mm is 63±3.3MPa, 2 mm is 33.1±5.3, and Lava™ with thickness of 5 mm is 29.2±2.2 MPa.
Conclusions: The thickness of Lava™ core materials has a significant effect on its bond strength to VITA VM9®.